"We might as well, in reference to the principles of each, attempt to separate surgery from medicine, as insist that either of these arts, in theory, is essentially different from the veterinary: every day's experience serves to confirm this our belief, and in showing us how often the diseases of animals arise from the same causes as those of a man, exhibit the same indications, and require a similar method of cure. "The science of medicine, like others, consists of a collection of facts of a common and not a specific character. These, therefore, admit of arrangement into different systems, according to the notions of theorists, and the various species of philosophy, brought to bear on the subject. "The first regular system was founded by Hippocrates, about three hundred and eighty years before Christ. It was founded upon _theory_, and comprised the doctrines of the ancient dogmatic school. Its pathology rested upon a supposed change of the humors of the body, particularly the blood and bile; and here are the first elements of the '_humoral pathology_.' Its remedial intentions were founded upon the existence of the _'vis conservatrix' et 'medicatrix naturæ;'_ and, although often maintaining direct antipathic principles of action, it rested mainly on physo-dynamic influence for the accomplishment of its therapeutic purposes. "About two hundred and ninety years before Christ, Philinus of Cos introduced the ancient _Empiric System_, which was founded upon _experience_ and _observation_. About one hundred years before the Christian era, the _Methodic System_ was introduced by Asclepiades of Bithynia. This system was got up with an avowed opposition to that of Hippocrates, which was called 'a study of death.' Themison of Laodicea, pupil of Asclepiades, gives an exposition of the fundamental principles of the methodic system; and it seems that all physiological and pathological action was considered to be dependent upon the _strictum_ and _laxum_ of the organic pores, or increased and decreased secretion, and that all medicines act only on two principles, _i. e._, by inducing contraction and relaxation, or an increase and decrease of the secretions. "It would seem that, in the first century of the Christian era, the methodic system was divided into various subordinate ones--the _Pneumatic_, _Episynthetic_, and _Eclectic_. The pneumatic system, which was the most popular of the fragments of the methodic, was most indebted to Athenæus of Attalia for its successful introduction. This system contemplated the doctrine of the Stoics, which recognized the existence of a spirit governing and directing every thing, and which, when offended, would produce disease; hence the name _pneumatic_. The indications of cure were more _moral_ than _physical_. Fire, air, water, &c., were not considered elements, but their properties--heat, cold, dryness, moisture, &c.--were alone entitled to the name.